Current digital cellular systems such as the Global System for Mobile Communication (GSM) or the Digital Cellular System 1800 (DCS-1800) in Europe, and the Personal Communication Networks (PCN) planned in the U.S. support mainly voice, message, and low-rate connection-oriented data services which are not well suited to support packet-based data communication.
Many mobile computer applications, however, require infrequent transfers of single or multiple data packets over the radio link of the mobile communication system. Some of them, e.g., e-mail, tele-shopping and tele-banking, and vehicle-dispatch or fleet management applications may be well served with a store-and-forward short message service. Others, among them terminal emulation, remote access to local area network (LAN) based servers, or credit-card verification require interactive usage, tolerate little delay, and are characterized by a wide distribution of packet length. There is little doubt that future mobile telecommunication systems such as the Universal Mobile Telecommunication System (UMTS) will have to support such data applications with an efficient packet-data service. In fact, the European Telecommunication Systems Institute (ETSI) is already in the process of defining such a service, called General Packet Radio Service (GPRS), as an extension to the current GSM system.
In the sequel, we will consider connection-less packet-data services for UMTS and PCN systems. In particular, we focus on the UMTS system which was developed in a code division testbed (CODIT) project under the umbrella of the Research in Advanced Communications in Europe (RACE) program. The CODIT system employs spread-spectrum transmission and code division multiple access (CDMA) and supports voice, message, and connection-oriented data services. For more details on the CODIT system please refer to "Design Study for a CDMA Based Third-Generation Mobile Radio System", A. Baier et al., IEEE J. Selected Areas Commun., Vol. 12, 1994, pp. 733-743. CDMA systems are of particular interest because they promise higher capacity and more ease of deployment than competing time-division multiple access (TDMA) systems.
It is an object of the present invention to provide a method and apparatus which enables CDMA-based UMTS and PCN systems to support a connectionless packet-radio service.
It is a further object of the present invention to provide a communication system with added functionalities.